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This is a guest post by Luke Surl, a PhD student in the Centre for Ocean and Atmospheric Sciences (COAS) at the University of East Anglia, where he is researching the atmospheric chemistry of volcanic plumes. You can find him on Twitter, or visit lukesurl.com for his excellent science-inspired comics.

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Last week a giant purple blob descended upon East Anglia, with commotion and a flurry of newspapermen in its wake. The vulnerable were told to shelter in their homes, powerless to tackle its all-pervasive reach. Wisdom was sought from the sages of this ill-understood art, but all that could be done was hope the blight would soon pass.

Smog over Norwich (iWitness24)

A little dramatic license is appropriate for a guest blog, no? To decode, the purple blob is the region of “Very High” air quality risk shown on the official maps that have been appearing this week. These maps have been accompanied by warnings for asthmatics and others sensitive to such conditions. The “sages” are the atmospheric scientists who, normally eclipsed in the media spotlight by their climatic colleges, have been ubiquitous on in the media.

If you haven’t been keeping track, in short a combination of factors conspired this week to cause parts of Britain to experience an usually high level of particulate matter. Britons were breathing dust blown in from the Sahara, plus some with old-fashioned home-grown pollution. The weather slowed the dispersion of this event causing it to linger and intensify.

While “smog” seemed to be the media’s favoured term for the phenomenon, (evoking memories of the London smog of 1952) the discussion amongst the atmospheric scientists at UEA (where I do research) was of the aerosol counts. “Aerosol” is a catch-all term for solid and liquid particles suspended in air, and there are, critically two sorts. We deem primaryaerosol particles directly emitted to the atmosphere whilst secondary aerosol are particles which form in-air from gaseous beginnings

The Saharan dust we have been inhaling is primary. Secondary aerosol is most readily created when the air has been polluted with sulphur and NOx. On an ordinary day, road traffic is the biggest such aerosol offender. In London, one of the principle raison d’etres of the congestion charge is to prevent such an air quality hit in a concentrated metropolis of cars and people.

Such technical distinctions are, however, largely ignored by ones lungs. Particles smaller than 10 micrometers in diameter travel into the lungs. The smallest of these can end up penetrating and settling deep into the respiratory system. This is not good news for anyone, especially asthmatics and others with similar conditions.

In some of the more morbid papers that atmospheric scientists are likely to come across, this air quality impact can be quantified. A 2009 study found Americans living in the most polluted areas can attribute air quality to their lives being about 2.5 years shorter than their cousins in cleaner areas. In China, where the economic boom has been quite literally dulled by thick smogs in its cities, the numbers are quite terrifying. These numbers are difficult to process. They are cold, dispassionate and cryptic, buried in journal papers few will read. But every data point hides an individual tragedy of a life extinguished early

Thankfully Norwich and London are nowhere near Chinese levels, though there are still thousands of such deaths a year. Britain, and the EU in general, quite rightly holds itself to very high standards with regards to its air.

As in everything, the recent incident has had a political dimension. Public debate has asked whether this incident is to be blamed on natural or human causes.

This misses the point. While the primary aerosol from the Sahara and the directions of the winds are beyond the remit of any public policy. But this natural phenomenon is compounded by human action. Regardless of how we apportion the blame, the particulates owing its existence to our cars and factories isn’t made harmless or insignificant by their natural counterparts, rather they can make a bad problem worse, especially for the most vulnerable. And even when the winds change and the purple blobs and media disperse, this pollution can still chip away days, months or years from human lives.

There’s nothing more essential to human life than the air we breathe, which is partly one of the reasons I have chosen atmospheric science as my field of research. It’s also fundamentally something we cannot help but share with our neighbours and community. Our air’s pollution and perturbation, from nature and from man, is something that will impact us all.

The issue of manmade global-warming seems far removed from questions of exoplanet habitability but there is a close link. A planet whose climate is highly sensitive to greenhouse-gas changes is also a planet that responds strongly to increasing heat from its aging star; and it’s hard for such a world to remain habitable for long. The Earth seems to be one such world (that’s why global warming is such a threat) but it has never-the-less remained habitable for billions of years. How it managed pull off this trick is an intriguing, but not particularly new, mystery.

In 1972 Carl Sagan and George Mullen recognized that, since our Sun produced 30% less heat when she was young, surface temperatures on the early Earth should have been far below freezing. However, geological evidence showed running water when our world was just a few hundred million years old. Sagan and Mullen called this the faint young Sun paradox and, forty years later, there is still no consensus on how to resolve it. However the concept of climate sensitivity, an idea refined over the last thirty years by climate scientists interested in anthropogenic global-warming, now gives us a clear framework for discussing the issues.

Climate sensitivity tells us how much warmer a planet becomes for a given increase in the heat it receives. It’s a bit like going from gas-mark 5 to gas-mark 6; how much hotter does this make an oven? At gas-mark 6 more gas is being burnt and temperature rises but, in a badly insulated oven for example, the increase would be less than expected. Similarly, different planets warm up by different amounts for a given increase in heating and this difference in climate sensitivity depends upon the relative strengths of positive and negative feedbacks in the climate system. As I’ll show below, the faint young Sun paradox occurs because Earth’s high climate sensitivity is incompatible with the flowing of liquid water on her surface when she was young.

Climate sensitivity is usually expressed by how much warmer the Earth becomes if carbon dioxide concentrations are doubled. Doubling of CO2 is expected by the end of the current century and so this is a very concrete way of expressing the expected impact. The best guess is that climate sensitivity is in the range 1.5-4.5 °C . This range is largely based upon computer models of the present-day climate system but it is backed up by simulations of Earth’s past climate which only match observations when similar climate sensitivities are used . If anything, these geological studies suggest that the computer estimates are too low but let’s be conservative and stick with the computer models. What does a climate sensitivity of 3 °C predict concerning temperature changes over the life time of our planet?

To calculate this we need to re-express climate sensitivity in a slightly different way. Doubling CO2 increases heating at the Earth’s surface by 3.7 Wm-2 but, to produce an equivalent amount of heating at ground level, solar radiation must go up by 5.3 Wm-2 because some is reflected back into space. Thus, temperatures go up 3 °C if solar heating increases by 5.3 Wm-2. Earth’s climate sensitivity is therefore 0.6 °C per Wm-2. Heat from the Sun has actually gone up 90 Wm-2 over the last 4 billion years and so temperatures should have risen more than 50 °C. This implies a young Earth that endured average temperatures near -40 °C and that is inconsistent with liquid water anywhere on our planet’s surface.

An obvious objection to this analysis is that the ancient climate system was very different to that of the modern Earth and so the present-day climate sensitivity may not be relevant. That’s a fair point but we can get around it by concentrating instead on the Phanerozoic Eon (i.e. the last 542 million years) when there is no reason to think that climate sensitivity would have been massively different to today. Solar heating has increased 15 Wm-2 over this time and so temperatures should have risen by about 10 °C but there is no evidence whatsoever for such a rise. Analysis of oxygen isotopes in ancient marine organisms suggest that Phanerozoic temperatures have fluctuated around a steady mean or perhaps even dropped a little. Thus, whether we look at the whole of Earth’s history or just the last half-billion years, there is no evidence for the expected overall warming despite the steadily increasing luminosity of our Sun. What’s going on?

The missing part of the puzzle is that Earth itself has evolved, both geologically and biologically, during its long history. For example, the slow growth of the continents and the biological evolution of more effective rock-fragmenters (e.g. lichens and trees) has steadily increased the efficiency with which CO2 is removed from the atmosphere by the chemical reaction of acid-rain on volcanic rock. Another greenhouse gas, methane, has also greatly declined through time as oxygen levels have grown following the evolution of photosynthesis. Furthermore, land, especially plant-covered land, is more reflective than sea and so, as the continents grew and as they became colonized by life, more of the Sun’s heat has been reflected into space. These processes, and perhaps others, cooled our planet as the Sun tried to warm it.

Two opposing forces therefore fought for dominance of climate trends and, coincidentally, roughly cancelled out. But what produced this coincidence? Some would ascribe it to the Gaia hypothesis that a sufficiently complex bio-geochemical system will inherently produce environmental stability. However there’s no credible mechanism for this and, in any case, Gaia may have confused cause and effect: Earth’s complex biosphere didn’t produce a stable climate; rather a stable climate was a necessary precondition for a complex biosphere. If this is right, then biospheres whose complexity and beauty rival that of the Earth will be rare in the Universe. On the majority of those few worlds where life arises, it will all-too-soon be frozen by bio-geochemistry or roasted by its sun. However a few worlds will, purely by chance, walk the fine line between these fates long enough for intelligent life to arise. We live on one of those rare, lucky planets.

Following the latest release of leaked emails from the Climatic Research Unit (CRU), many people here in the department braced for the impact that the release would have on their work, their reputations and their university. Expecting a furore similar to that experienced in 2009, the hatches were battened down and the crew took shelter, weathering it as best as they could and waiting for the storm to pass. This time, the storm never came.

"Some heavy denial is expected, with a good chance of scattered bullshit."

The UEA dealt with the leak quickly and much more effectively. Also, the emails aren’t new, they seem to have been stolen at the same time as the original hack, and you’d therefore expect that all the ‘juicy’ newsworthy media-bites had been fleshed out during the first round of the airing of scientists dirty laundry. As far as I can tell, the release was so anticlimactic that even notorious ‘sceptic’ Anthony Watts is struggling to extract much meaningful or significant smear-worthy material from an extensive database of boring personal emails. It’s almost embarrassing that it’s so pathetic; at least people were talking about the release before, it definitely put the UEA on the map and on the tip of people’s tongues in 2009 but this time round it’s dropped off the mainstream news radar quickly and in a big way. There is no substance and therefore no story. The Guardian and the BBC are still providing some minor coverage but even the Daily Mail, a British tabloid known for their extremely loose grasp of science (lest we forget the ‘Supermoon’) and climate denial (strange those two often go hand-in-hand?), seem to be growing weary of this seemingly endless tirade of guff.

What is obvious, as it has been to many before but is laid bare for all to see now, is the patently political motivation behind the release. It was obviously timed to coincide with the UN Conference on Climate Change in Durban on the 28th of November. The science, as many people know and accept, has been repeatedly vindicated by independent review and inquiry by scientific and parliamentary committees, most recently by the physicists of the BEST study, the results of which our friend Mr Watts famously claimed he would accept regardless of their findings. His lies aside, there was no ‘wheeling-and-dealing’ going on behind the scenes and no global scientific conspiracy was uncovered. It is no longer about the science, that much is evident. What is clearer now than ever before is that this is a smear campaign, pure and simple, employing immature character assassination in a rather desperate attempt to over-hype an already dead story. All the emails showed was that scientists are people too; they bicker amongst each other, their egos clash and they criticise one another’s work. This is what you would expect, and the more criticism the better – that’s how science gets done.

I assume that the point of this whole futile exercise is to attempt to undermine the scientific consensus and manufacture a debate that doesn’t exist. The motivation behind this comes from a number of areas I guess – fear, vested commercial interests, wilful ignorance, attention-seeking etc. If this was indeed the aim, their ploy has failed monumentally. The fact that no one seems to care may be a mixed blessing though. On one hand, the public are bored of this conspiracy and continuing to flog a dead horse isn’t inciting the level of backlash the denialists were attempting to produce, which is great and means that scientists can get on with their jobs. However, this may be the perfect opportunity to go on the offensive and expose the ‘sceptics’ for the delusional, corrupt trolls they are; the timing of the release is no coincidence, and as the science is sound it can no longer be a case of a noble whistle blowing minority speaking out against the engrained vested interests of career scientists. The painfully blatant, transparent and unequivocal fact is that is release is about politics, not science, and good scientists who are tired of having their names unfairly dragged through the mud for political gain should stand up and speak out against this juvenile smear campaign.

Around 2.3 billion years ago our planet underwent what was perhaps the most significant and dramatic revolution in its history. However, this was not a revolution that we may be familiar with. There was no political basis to this transition, perhaps involving a suppressed population rising up in unison against a brutal dictator. This was a revolution was on a truly global scale and it was instigated by the chemistry of the planet. In this case, and quite literally, change was in the air.

During much of the Archean eon, between 3.9 and 2.5 billion years ago, the composition of the atmosphere of the Earth was dominated, as it is today, by nitrogen, but also by gases such as methane and hydrogen sulphide. These gases are ‘reducers’ (as opposed to ‘oxidisers’) that ‘donate’ one of their electrons to another substance in reaction. Oxygen, an oxidant, was a minor constituent, representing less than one part per million (1 ppm) of the atmosphere. About 2.3 billion years ago however, this all changed. This momentous and eon-defining event is known as the Great Oxidation to earth scientists, and it represents a truly life-changing transition in the history of the planet. Oxygen concentrations jumped (in relative terms) to between 1 and 10% of the present atmospheric level (PAL for short).

The puzzling thing however, is that oxygenic photosynthesis (OP) had already been active in primitive cyanobacteria (similar to the one above) for at least 300 million years before the Great Oxidation, originating sometime between 3.2 billion and 2.6 billion years ago, with the most convincing evidence placing its genesis at 2.7 billion years before present. Organisms had evolved the extraordinary ability to use photons of light to split water molecules and combine them with carbon dioxide to form complex sugars, in the process releasing oxygen gas as a by product. The evolution of oxygenic photosynthesis was in itself an incredible feat, involving some of the most complex cellular biomachinary ever discovered. Why, then, was the atmosphere of the early Proterozoic eon so oxygen-poor?

The answer, it turns out, is a rather complicated one. Oxygen concentrations during the transitional period before the Great Oxidation, but after the evolution of OP, were spatially variable, concentrated around the organisms responsible for its production as a waste gas. Any oxygen that made it into the air was quickly destroyed by reaction with methane against the backdrop of a highly (ultraviolet – UV) irradiated atmosphere. The reductant-dominated atmosphere was a product of volcanic out-gassing which provided a constant source of reduced gases such as hydrogen, hydrogen sulphide, methane and carbon dioxide. Any oxygen that wasn’t destroyed by reaction with these gases was mopped up by the large swathes of reduced material likely to be present on the surface of the Earth – including iron and iron pyrite (which was transformed from its reduced ferrous state to its oxidised ferric form) and resulting in the iconic banded iron formations (or BIFs) associated with this time. It would appear that oxygen could not maintain a foothold in this reducing world, struggling to maintain a low concentration which would have been spatially patchy and probably variable in time as well. Its sources were balanced by its sinks, as the chemists say.

In order to come to dominate, something would have to break the cycle – an imbalance between the sources of oxygen (i.e. the oxygenic photosynthesisers) and its sinks (methane photolysis and reaction with reduced gases and material from the mantle). Luckily for us as oxygen dependent organisms, something did break the feedback loop and that something was the humble hydrogen molecule.

Hydrogen in its elemental or ‘free’ variety is a reductant, reacting excitedly with oxygen to form water vapour, but in the upper atmosphere it behaves rather differently. At the base of the atmospheric homopause, around an altitude of ~ 100 km, water vapour is absent – frozen out at the stratospheric ‘cold trap’ at 20 km, but hydrogen molecules can be found hitching a lift within the structure of the methane molecule (CH4) which is light enough to rise through the homopause. The methane molecule is attacked by the UV-generated radicals in the upper atmosphere (O, OH) and yields hydrogen atoms that can diffuse right to the very top of the planetary atmosphere, known as the exobase, at around ~ 500 km. Here, some of the light hydrogen atoms – the high energy tail of the distribution – are accelerated to a velocity that allows them to overcome the gravity of the Earth and permanently escape into space. This mechanism, over millions of years, resulted in a net increase in oxygen by the erosion of a finite hydrogen (reductant) reservoir, pushing the balance of sinks and sources of oxygen to the side of the sources. This process is still occurring on the Earth, but at a much lesser rate than in the past due to the fact that methane is now less abundant than it once was.

At a critical point, estimated to be around 1 ppm by volume of oxygen, an ozone layer began to form in the stratosphere. This layer served to shield the Earth below from UV light and thereby prevented the reaction of methane and oxygen in the lower atmosphere, shifting the balance in the favour of oxygen once again and increasing its concentration further still.

The age of oxygen had dawned.

Perhaps I disposed of the political revolution analogy too soon. Let us think of oxygen gas as a suppressed minority but with the great potential to usher in a new age of organism diversity and to completely revolutionise the Earth system. Methane & co. form the oligarchy of the reductants, dominating the atmosphere and violently reacting with any oxidants they encounter (using their oppressive, ruthless army of UV light) to prevent an oxidising majority from forming. They insist upon the use of traditional, inefficient metabolic pathways such as hydrogen sulphide fermentation to power the small, putative organisms over which they rule. But the agents of change, the oxygenic photosynthesisers, are working studiously to infiltrate the atmosphere and gradually, with the protection provided by the revolutionary guard molecule, ozone, they eventually overthrow the reductants, banishing them to the depths of the oceans, lakes or the guts of cows and ushering in a new age of glorious oxygen domination!

Of course, this is just a metaphor and not a particularly good one at that. The real revolution took hundreds of millions of years and firmly without the inferred teleology or determinism that stems from my anthropic bias. Oxygen is a poison, and to the majority of life on the early-Earth, the dawn of the Great Oxidation marked the end of their reign as surface dwelling organisms. However, without it complex organisms would not have evolved. Anaerobic respiration is several orders of magnitude less efficient and therefore unsuitable for powering large, complex bodies that require more energy – energy that can only be provided by an oxygen metabolism.

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Much of the information and insight for this post comes from Tim Lenton and Andrew Watson‘s excellent book, Revolutions that Made the Earth, which was published last year. It is available on Amazon.

Complex fractal vein branching patterns of a single leaf. (Photo by Mark Boucher)

Imagine, you – as a thinly veiled metaphor for early primate consciousness – are wondering the lonely, empty landscape of ignorant oblivion at the beginning of our species’ sentient awakening. You are not aware of your passage through space and time and subjectivity and introspection are, for now, well beyond of your reach. Now let’s propose that in this hinterland you found a leaf. Let’s also imagine that you’ve never seen one before. Ever. I know, I know. But pretend, if you can. The leaf in isolation provides you with little information beyond that of its physical form: its shape and colour. You know and understand nothing of its inner workings.

Later, with the basic comprehension that the lonely leaf provided fresh in your rapidly evolving memory, you find another leaf, but this time it is attached to a branch. You now discover that you have a little bit more information, visual and potentially behavioral, about what exactly the leaf has evolved to do, even though at this stage you understand nothing of the theory of evolution by natural selection. You now realise that the leaf is part of a larger whole, the stick, but yet you still understand little of the why the leaf, and now the stick exist, aside from the basic fact that they do. Your unwillingly ignorant self cannot yet process the deeper philosophical connotations of this curious observation.

You then stumble across a tree. The tree encompasses many sticks, all playing host to many more leaves. The complexity of the information that you are processing is increasing, as is your understanding of it. You realize that the tree is the sum of its constituent parts, and you may even take a purely hypothetical, completely untestable philosophical stab-in-the-dark at how it works, and why it’s here. You may be right, but it’s unlikely at this stage as all your conjecturing and hypothesising is based on incomplete evidence and basic observational logic. Nevertheless, a guiding torch of rationality has been lit; the match, human curiosity.

You now begin to appreciate the role of the whole organism within the environment – the leaves feed other animals, animals that you in turn can eat. Its fruit can also feed you and your family. You surmise, completely logically, that bigger fruit means more food. You begin to postulate the mechanisms behind what makes fruit bigger, and attempt to exploit this fact to your advantage. You may now also realise that trees only grow in the sun and with sufficient nutrients, and determine that sunlight and fertiliser are directly involved in the process of providing this organism with vitality. Your understanding is increasing, going beyond the purely visible, physical structure of the tree, and into the biology, into the inner workings of the organism. Through trail-and-error and basic observational analysis, agriculture is now within your grasp.

But increasing information doesn’t necessarily correspond to increasing spatial scale. The microscopic sphere increases the possible complexity of the organism by several orders of magnitude. You can uncover the organs and cells of the plant and their constituent parts, right down to the smallest, subatomic particle. You discover that the tree harbours the ability to harvest energy by using photons to split molecules of carbon dioxide and water to form complex sugars and that it emits a metabolic waste product in the form of oxygen gas.

The trend towards increasing complexity continues when you discover that you can increase your computational abilities beyond that of your own intelligence by passing complex tasks on to other organisms, in our case computers, that are better equipped to deal with this greater complexity, thus revealing more and more information, and more and more levels of complexity and interconnectedness. Organic ‘coding’ (DNA) is discovered, and the organism can now be artificially modified and genetically engineered by using our outsourced processing units to suit the basic requirements of an increasingly populous species. Drought and pesticide resistant, larger and more rapidly growing than before, we have altered the properties of the now unrecognisable organism by unnatural selection, not in order for the organism to best exploit its environment, but rather to assist us in exploiting ours. We have moved on from being absorbers of information, to manipulators and creators; we have taken the leap from observational to applied-intelligence.

Our understanding of the complexity of this organism, and by implication the path of discovery itself, has been fuelled by the comprehension of ever increasing information marching in evolutionary tandem with our increasing abilities in information processing. Increased information input, naturally selects for increased processing and computation abilities, if that means that the organism will be better adapted to survive and flourish in its environment. If so, gradually increasing intelligence will eventually culminate in a sentient, highly intelligent species.

That’s us. You and me. Humans: borne from the information gleamed from a lonely leaf.

It may be difficult to believe that in this era of globalised culture, telecommunication and corporatism that there are places on our little planet that remain untouched by our worldwide civilisation. Places where human beings exist completely outside of our realm of influence. But these people do exist in many parts of the world, from Asia to South America, Australia to Mexico and even the United States. These societies are anachronisms of a time long past, a window into the lives of our ancestors; their entire knowledge and existence, their microcosm universe and everything they know is completely alien to us, and we to them. Everything you know, everyone you have ever met, every technological comfort, philosophical or religious belief and every single word you think or speak is utterly, completely and entirely alien to these people. All of our trivial issues, our politics and meaningless everyday routines are incomprehensible to groups of humans that are alive today.

States containing uncontacted peoples (Wikimedia). Uncontacted tribes exist in nations across the world, from South East Asia to North Sentinel Island off the coast of India. However, most isolated peoples inhabit the vast expanse of the dense Amazonian rainforest.

In February 2011, the Brazil National Indian Foundation (also known as Funai), aerially photographed for the first time an isolated Amazonian tribe living in a protected area on the border between Peru and Brazil. These are extraordinary humans who have had extremely limited, if any, contact with any other humans or society; they are completely isolated and insulated from our way of life: our science, technology, politics, our celebrity fetishes and economics. They exist in a world separate to the one that you and I share. Bounded by vast expanses of pristine Amazon rainforest but still spatially contiguous with ours, their world is separated culturally, linguistically and religiously from our own.

A village of uncontacted indigenous people in Brazil, 2008. (Funai/Gleison Miranda)

We know very little about these people and how their society is structured. We can gleam some superficial information from these remarkable images, mainly regarding their diet, which seems to consist of bananas, papaya and manioc sourced from communal gardens. Whilst there is some evidence from the images of inter-tribal trading, contact with outside peoples is unheard of. We know nothing of their religious beliefs and have no means of uncovering the intricacies of their language or culture. We should not consider these tribes to be ‘primative’ however. They appear healthy and, from what little can be inferred from the images, are thriving in one of the most extreme and hostile environments on Earth. Given the availability of resources, their weaponry is impressive and effective; some bows up to 4 metres long with 2 metre arrows have been recovered from abandoned villages. They are adorned in red dye (known as urucum) from the annatto shrub, which presumably has some cultural signficance. We should therefore recognise the universal adaptability of the human species to all environments and our common desire for survival and persistence.

Contact with these tribes should remain completely out of the question. Often, as with the inhabitants of North Sentinel island in the Bay of Bengal, uncontacted peoples are fiercely territorial and will attack and kill outsiders on sight. Crucially, they possess no immunity to Western infectious diseases such as the common cold and mortality rates would be extremely high if these diseases were to spread to their tribe. History provides many tragic examples of the decimation of previously isolated populations by the contraction of diseases after contact with other tribes or explorers. Campaigners for the rights of uncontacted peoples cite the fact that they also have the right to self-determination and like all humans have infallible rights that should be protected. Illegal logging, mining and ranching in the Amazon rainforest is placing increased pressure on the environment, and bringing the prospect of unplanned and unintentional contact with these tribes closer. The likelihood, as has happened many times in the past, is that is that if contact is made with these people it will lead to the collapse of their society; either through hostility towards the armed clandestine loggers and ranchers, or through demographic collapse via the inevitable waves of epidemics likely to sweep through their village. It is therefore imperative that governments act now to protect these people, their lands and their way of life to give them a chance at shaping their own destiny and to preserve their culture.

Bruce Parry, campaigner for Survival Internationaland BBC journalist renowned from his work with indigenous peoples across the world as the host of documentaries such as Tribe and Amazon,summed up the situation very poignantly: “Protecting the land where uncontacted tribes live is of global importance. We have consistently failed to introduce them to our world without inflicting terrible traumas. It is for them to decide when they want to join our world. Not us.”

From the comfort of temples and churches at the dawn of our intellectual awakening, our ancestors sought meaning – as we all do – a purpose, a reason for our existence and how we came to be. At that time, lacking the considerable collection of knowledge that we now possess, they developed some elaborate theories to explain how we as a species were conceived. Religion is a defining feature of all human societies, the representation of our primitive unilateral search for truth and understanding. It provided the social adhesive that brought people together as a community. Today, some still remain in that primitive mindset, despite all our achievements. They cannot accept that we are just another terrestrial species vying for dominion over our competitors, albeit with a particularly effective evolutionary strategy. We arrogantly assume that we are the purpose of everything that has come before, and that will come after, akin to gods walking the Earth. All this despite being extremely late-comers to the life-on-Earth party.

Creationism, in all its ugly forms, is fundamentally boring and intellectually lazy. Despite being dogged by logical fallacies, inconsistencies and contradiction, it continues to linger on amongst those unable, or unwilling, to accept simple, incontrovertible truths regarding our existence. An anachronistic throwback to a simpler, earlier stage in our societal and intellectual development conceived in a time long before the enlightening torch of scientific discovery was lit. At the time, the authority of the politico-religious ruling elite was unquestionable and organised religion was the tool used to extract loyalty and revenue from their citizens. Accordingly, creationism is the antithesis of science – it encourages intellectual complacency by providing a disappointingly simple and vague explanation for everything that has ever happened and that will happen in the future, without any evidence whatsoever, and on the basis of empty, unfounded and unrewarded faith. Those who continue to subscribe to this obviously outdated belief system contribute nothing – and in fact substantially subtract – from collective human intellectual endeavour and curiosity. Creationism will never achieve anything, save to revert our young societies to superstitious and bigoted tribal communities, feeding off our primitive irrationality until we are once again feeling our way through the darkness of existence with no guiding light except the dim candle-light offered by weak philosophies of a time gone by. Vitriolic creationist rhetoric is the water to the torch of understanding; it extinguishes the flame of rationality and keeps us rooted in the past.

Those of a more liberal religious disposition who have the (preferential) good sense to view the Genesis saga as a myth, as well as the rationally minded amongst us, are fully aware of the true driver of speciation amongst organisms – evolution by natural selection. It is a theory, but in the same sense that the laws of gravity are a theory. Evolution is by all reasonable grounds, and to a significant degree of certainty, a fact, and natural selection is its very effective mechanism, albeit a very indifferent and cruel one at that. It is supported by a body of evidence that is undeniable in its enormity, housed in every natural history museum and within the genetic code of every organism. It is happening now and we can observe it in action.

In a very simplistic and reductionist definition of this mechanism, the passage of genetic information and the phenotype it codes for, probably acting at the level of the gene, is ensured by the successful reproduction of the organism that possess it. The level of reproductive success of a given organism is proportional to its environmental adaptability – a well adapted organism will most likely be the most successful at gathering resources, and therefore the most likely to pass on its genes to its descendants. Natural selection is not teleological, it is indifferent to subjective human notions of cruelty and suffering, but it is efficient and powerful, probably so much so that if life was to exist on another planet it too would most likely be driven by natural selection. In that sense, evolution by natural selection is a universal constant, akin to the laws of gravity or thermodynamics, constant throughout space and time.

It probably didn’t happen like this…

Consider, despite the unforgiving unpleasantness involved in so doing, the innumerable organisms that have been destroyed by predation or competition throughout the vast expanse of time that life has existed on this planet. Pause to imagine the indescribable suffering wrought by one organism upon that of another; the agony and fear, the venom and spines, teeth and tools that contributed to their destruction. The sick and old, feeble and weak, their fleshy frames easily torn by tooth and claw, brittle bones of calcium snapped by rock, their bodies poisoned by toxins and withered by age and disease. Viruses abound, DNA replication fails and cancers malign. The accumulation of all of the pain and suffering, the collective agony of all creatures killed by predators, enemies, competition, disease or themselves, expressed as a whole would be impossibly traumatic to even begin to comprehend. A tireless, indifferent and endless cycle of birth, death and decay.

Prior to our self-domestication and effective removal from the pressures of natural selection, Homo Sapiens was originally a raptorial species that hunted in packs using tools and superlative cunning to ambush and assault our prey. Short-sighted and nimble, we were efficient hunters and could run at a moderate pace for an impressive duration to exhaust our pursued prey and make the kill. Not many individuals of the species continue to hunt at present and most have descended into physically feeble, fat and sloth-like creatures living communally in enormous nest-like artificial structures, usually perched on a coast. We still squabble violently over resources, reproduce prolifically and alter our environment to suit our short-term needs, occasionally to our long-term detriment. Epitomised by our superior intelligence we are the culmination of millions of generations of successful organisms. We are very effective at adapting to our environment using superlative ingenuity to circumvent our otherwise relatively feeble physical endowments. However, we are in many ways imperfect organisms blighted by defects, psychosis and degenerative disorders and we carry with us several items of evolutionary baggage that are now unessential.

Why would a benevolent Creator choose this long-winded, brutal and imperfect mechanism as His ideal path to eventually culminate in the dominance of His image on Earth; the sentient, introspective evolutionary pinnacle that is Homo Sapiens, over 3.5 billion years after life first emerged? Those who invoke the notion of a loving, omnipresent Creator, even in the most liberal of interpretations, surely have to at least pause for thought upon considering this unspeakably horrific reproductive strategy, as admittedly effective as it is.

In light of this, the continued belief in creationism, in all its guises, is so nonsensical and so deeply flawed in its reasoning and rationale that it could be considered a serious defect of human nature because of its very real ability to stunt our continued dominance as a species, and therefore tantamount to an evolutionary failure. Or, perhaps it could too be an evolutionary mechanism; religion may be a means to deal with the occasionally unnerving level of comprehension and foresight that a superior intellect affords us. We all want to be saved after the agony of death, to have a loving protector guiding us at every step, to one day achieve a higher sense of understanding and purpose. It eases the pressure applied to our psyche by the apparently uncomfortable knowledge of our desperate mortality and isolation.

This is no excuse however. We should not be seeking shelter in ignorance, however comfortable its embrace. It is within our species’ best interests to deal with the matter of our existence with rational forethought and in as objective means as possible, however unpleasant or humbling our findings may be.

This essay is based on the Greater London Authority’s Climate Change Adaptation Strategy, which can be found here

The London Climate Change Adoption Strategy was published in 2008 by the Greater London Authority (GLA) and outlines the likely effects of global climate change on London, with particular reference to risk assessment and understanding, long-term management, emergency planning and public policy issues. Drought prediction and water management in the Thames Valley is given emphasis as a very serious concern for the future sustainability of London. Several authors, (notably: Hennessy et al. 1997; Blenkinsop and Fowler, 2007 and 2007a; Hirabayashi et al. 2008; Hulme et al. 2002 and May, 2008) have attempted to quantify the effect of greenhouse gas induced climate change on precipitation frequency and intensity in the near and distant future under various scenarios. The general consensus is that both the frequencies and the length of dry spells are likely to increase in the future. However, drought variability over the past century has changed very little (Hughes and Saunders, 2002; Hisdal et al. 2001 and Easterling et al. 2000) indicating that perhaps more understanding of both drought and climate change processes, as well as the intrinsic relationship between the two, is required.

Hisdal et al. (2001); Hughes and Saunders (2002) and Easterling et al. (2000) all conclude that whilst there is no indication that drought frequency and severity have increased across Europe over the last 100 years it is important to understand that the quality, drought parameters and spatial and temporal resolutions of the data strongly influences these results. Recently, several authors have used statistical and remote sensing models to illustrate and predict the frequency and severity of extreme events, such as drought, under various climate change scenarios. Notably, Hulme et al. (2002) predicts that whilst winter precipitation under all IPCC Special Report on Emissions Scenarios (SRES) scenarios (low, medium-low, medium-high and high) is likely to increase by a maximum of 30% by 2080, summer, autumn, spring and the overall annual average rainfall is likely to decrease considerably. Their findings are summarised in the table below.

SRES Emission Scenario

Summer Precipitation (% change)

Winter Precipitation (% change)

Annual Average Precipitation (% change)

Low

-20 to -30

+15 to +20

0 to -10

Medium – Low

-30 to -40

+15 to +20

0 to -10

Medium – High

-40 to -50

+25 to +30

0 to -10

High

> -50

+25 to +30

0 to -10

Whilst precipitation frequency during winter is predicted to increase, its intensity (amount of rainfall, per unit of time, per unit of area) is also set to increase, as shown by the figure below, from May (2007). This is significant as more intense rainfall events are likely to be more localised, shorter, have larger raindrop sizes and facilitate more rapid run-off processes which may not necessarily contribute to groundwater recharge.

Similar findings were reported by Frei et al. (1998). A warming of 2°C was predicted to increase the frequency of heavy (> 30mm day-1) precipitation events by 20%. Correspondingly, Easterling et al. (2000) concluded an increase in both one day and ‘multiday’ intense precipitation events would be ‘very likely’ across Europe by the end of the 21st Century.

Under all SRES scenarios, Hulme et al. (2002) also predict a significant increase in annual, summer and winter temperatures, with the greatest increase occurring during the summer months. This increase, coupled with the warming effect of the urban heat island (UHI) would serve to further exacerbate evapotranspiration and increase public water demand, putting further pressure on London’s water resources.

Water Resources, Demand and Drought Management in London

An annual average of 690 mm of rain falls over the Thames catchment. Of this, 455 mm (66%) is lost by evapotranspiration. Of the remaining 235mm, 129 mm (55%) is abstracted (the highest proportion of any catchment in England) and 105mm (45%) is allowed to flow back into rivers. 80% of London’s water is stored in reservoirs around the city after being extracted from the Thames and the River Lee. The remaining 20% is abstracted from groundwater stored in the chalk aquifer below the city. Groundwater recharge, which replenishes both the aquifer and the river network, occurs during the winter, when rainfall is at its highest and evaporation is at a minimum. Londoners, due mainly to increased prosperity and lower occupancy densities, consume 18 litres more water per day on average (168 litres person-1) than people in the rest of the country, yet the Thames region has a considerably lower water availability (265 m3 person-1 year-1) than the rest of England and Wales (1,334.1 m3 person-1 year-1). Although this clearly illustrates the value of the limited water resources in London, a further 600 million litres per day is lost through leakage caused by the aging water network, subsidence of the clay strata on which the network is laid, vibrations from transport and pipe corrosion.

The GLA report highlights some of the key areas of drought vulnerability in London and attempts to address these issues by identifying the risks and possible mitigation and adaption strategies available. Whilst addressing these issues is a commendable step towards sensible drought management, it is important to realize that these are merely theoretical concerns hypothesised on the basis of contemporary drought frequencies and intensities. Future drought events in London should be considered relative to the wider context of climate change across both the UK and the world. The GLA report, whilst going some way to documenting policy and planning initiatives, lacks the quantitative drought prediction capabilities in the vein of Hulme et al. (2002) and others.

If the predicted decrease of between 20% and 50% in summer rainfall in the UK due to climate change holds, this would put unprecedented pressure on London’s water network. Also, an increase in the intensity of winter precipitation would not facilitate the efficient replenishment of the groundwater store, further exacerbating drought conditions during the summer months. Whilst the UHI effect would undoubtedly intensify temperature extremes between the city and its surrounds, its effect on drought events seems uncertain. Increased hygroscopic pollution and convective uplift associated with urban canopy layer would serve to seed cloud formation and augment convective rainfall consecutively. The small increase (c.10%) in precipitation would be negligible when considered relative to the negative effect predicted to be caused by national and global climate change and would mainly affect downwind areas. Certain London-specific factors, such as the extremely high abstraction rate coupled with the below average individual water availability, the use of CSOs and river-fed cooling systems in power plants as well as leakage from aging pipes may also serve to intensify the social, economic and environmental implications of a drought event. The GLA report provides a concise policy framework for drought management but operates within the theoretical structure of past and/or present physical drought impacts. It also lacks any substantial quantitative drought prediction models and fails to identify a timescale for change which could be used to realistically assess and address the risks of drought in the City.

I fail to see it as a coincidence that many on the right of the political spectrum in the UK and USA, and elsewhere I’m sure, fail to acknowledge the mountain of evidence in support of the argument that climate change is happening, and it’s happening right now, and that humans are to blame. They call themselves ‘climate sceptics’ but this couldn’t be further from the truth. Scientists are the real sceptics here, as the scientific method essentially requires scepticism and objectivity of all theories and hypotheses. It requires rigorous testing of these assumptions, examination of the methodology, data analysis and conclusions and it requires these tests to be repeated again and again, until the either the hypothesis can be effectively rejected or the theory is accepted by the wider scientific community, not as fact, but as theory. A framework in which further work can be carried out, details examined and improved and further testing implemented. Climate change is now at this stage. It is a theory, yes, only a theory, but one that has been tested over and over, analysed and scrutinised from all angles by erudite scientists, with no vested interests except for the hope that we can avert the dangers that we are about to unleash on our only home. These are men and women who have dedicated their lives, careers and reputations to objective, scientific truth, or at least to get as close to the truth as it’s possible to be, not conspiracy theorists who have researched the topic on some obscure website for 20 minutes. They are people who are not prone to being alarmist, and in fact make every attempt to the contrary. The details may require work, but to continue to deny the basic fact that carbon dioxide is a greenhouse gas, and that the combustion of hydrocarbons by our industrialised society is releasing CO2 into the atmosphere at unprecedented levels is not sceptical, it’s frankly stupid.

There is no scepticism shown by the climate deniers, as I shall now refer to them. The evidence is there for them to analyse to their heart’s content. If they conduct the science properly they will come to the same conclusion as many before them have done. Instead, they tend to resort to argumentum ad hominem, as keenly demonstrated by the fiasco that resulted in the malicious publication of irrelevant, stolen personal emails from the Climatic Research Unit (CRU) at my old haunt, the University of East Anglia. If you can’t win the argument because the facts are just not on your side, why not resort to some good old-fashioned character assassination? In my mind, the whole debacle was not handled particularly well however. The CRU went on the defensive, refusing to release their climate data to just any old crazy person. At worst, this made them look like they had something to hide, or that they were aloof and indignant of those outside of the scientific community.

There are many and varied reasons that I can think of for why an individual or organisation would choose to ignore the veritable enormity of the evidence for anthropogenic climate change, the main one being, and in this respect I agree, that it’s bloody frightening. Humans base response to news of this gravitas, i.e. that the world may end and that it’s almost certainly our fault, is to go into a state of indignant denial, followed by anger directed at the messenger of said news, in this case the scientists. The unthinkable consequences of our uncontrolled climate tinkering will most likely result in the deaths of many, many people, mainly in the poorest countries on Earth, either from flooding, or droughts or displacement due to wars being fought over meagre resources such as water, fuel and food. Another reason that a sensible, if unwilling, person may want to continue to deny hard evidence to the contrary, is that is requires a rather drastic response from us, the members of the developed world, that would almost certainly alter the basic dynamics of our lovely, quaint way of life. We would have to make tough financial and societal compromises via an increased cost of living or taxation. We would have to abandon, or at least drastically alter our predisposition to all things hydrocarbon, be it our motor-friendly cities, or our polluting coal power plants. These are all things that would drastically and permanently alter the ‘status-quo’, that old conservative rhetorical mainstay, and this is enough to significantly upset a good proportion of the population.

The main point I’m trying to make is that this whole argument is essentially a one-sided political disagreement, if you can entertain such an idea. Those on the right have never been considered to respond rationally to most decisions, a fact that is often by their own admission considered as a strength. Science and academia in general are often considered to be broadly ‘liberal’ in their outlook, mainly due to the fact that science is often carried out in progressive, rational and forward-thinking way using novel technologies in an attempt to push the boundaries of human understanding. Needless to say, this is incompatible with conservatism and tradition. The climate change ‘debate’ is not an attempt by liberal scientists to turn our lovely planet into a green dystopia of carbon taxing and expensive airfares, despite being perceived as such. All that climate scientists are doing is reporting the facts, as they have always done and will always do in the future. Perhaps the facts should be provided to all that request them, regardless of their agenda, and I agree that this is the main failure of this entire scientific paradigm to date. It is obvious that there is nothing to hide, save the uncomfortable truth that we are inexorably altering the basic atmospheric chemistry of our planet, and this is a fact that should be available for all to witness first hand, given they have the training to carry out the analysis of data on this scale.

Let’s take a step back. Is it really such a bad idea to wean ourselves off our oil and coal habit? To breathe cleaner air and drink less-polluted water? No one can really say that coal and oil combustion is a pleasant activity that they would be happy to carry out in their own back yard. I admit that the transition will be difficult and expensive, but surely it will be worth it in the end? Besides, we’ll run out of those resources soon, perhaps even in this century. Even if there was only a tiny scrap of evidence, forgetting the huge repository of journal articles and papers available, I would still want to take the opportunity to avoid the catastrophic possibility that that evidence may be correct, especially if, in the process we provided a safer, cleaner world for generations to come.

Lake Kivu, on the border of the Democratic Republic of the Congo (DRC) and Rwanda, is unique in the fact that it is one of only three known ‘exploding lakes’ in the world, along with Lake Nyos and Lake Monoun, both in Cameroon. These lakes are so named due to the violent limnic eruptions they occasionally experience, which are caused by the sudden expulsion of significant quantities of carbon dioxide (CO2) and methane (CH4) from the lake depths into the surrounding atmosphere. By displacing the surrounding lighter, oxygenated air the heavier released gasses form a mazuku (Swahili for ‘evil wind’); an anoxic air pocket that proves lethal to wildlife and humans. The deadliness of the mazuku was brought abruptly to the attention of the world’s media on the 21st of August 1986 after a limnic eruption of 0.3 – 1 km3 of CO2 from Lake Nyos resulted in the asphyxiation of 1700 people and thousands of cattle. A similar, smaller eruption occurred late in the evening of the 15th of August 1984 and resulted in the deaths of 37 people in the low-lying regions around Lake Monoun.

Figure 1: Map of the Republic of Rwanda showing Lake Kivu on the western border with the Democratic Republic of the Congo (CIA World Fact book, 2011)

The exact cause of the cataclysmic release of CO2 from either of these lakes remains unknown, despite significant scientific interest in the aftermath of the disaster. The most widely accepted theory is that of the limnic eruption hypothesis; an as yet unknown trigger results in the local supersaturation and subsequent release of CO2 that has been accumulating the in water column. Under normal conditions, a vertical difference in the density of the water column confines much of the trapped gas to the deeper reaches of the permanently stratified lake. Beyond this, CO2 and CH4 concentrations increase with depth. A baroclinic disturbance in the local pycnocline, caused for example by a landslide, earthquake or volcanic eruption, could result in the creation of an area of intense local supersaturation and the eruption of these gases into the atmosphere. Although the limnic eruption theory is supported by observations of slow CO2 recharge after the Lake Nyos disaster, the possibility that the outgassing was caused directly by volcanic activity in the very tectonically active Great Rift Valley cannot be ruled out.

A report in Nature outlined the theory that magmatic CO2 diffusing into the benthic deposits at the bottom of Lake Kivu is fuelling the further production of CH4 by methanogenic bacteria in the sediment. It is now thought that Lake Kivu holds 300 km3 of CO2 and 60 km3 of CH4 at depths below 50 – 80 m, a respective increase of 10 and 15% since the 1970s. This gas reservoir is up to 350 times greater than that of Lake Nyos, the eruption of which would be devastating to the 2 million people that live along the shore of Lake Kivu. However, unlike Lake Nyos, concentrations of dissolved gases in Lake Kivu are thought to be below supersaturation at present and there are no plans to artificially degas the lake to reduce the probability of an eruption event.

Due to economic importance of the CH4 dissolved in Lake Kivu, and the uncertainties involved in its abstraction, recharge and volatility, the governments of the DRC and Rwanda recently jointly commissioned a technical appraisal of the viability of methane abstraction for power generation. Based on a 50 year economic yield, and using current estimates of gas recharge, the working group estimates that depending on the rate and efficiency of the extraction the methane reservoir in the lake could provide between 160 and 960 MWe (megawatts of electrical power), worth between US$7 and $42 billion at $100/MWh. This is a substantial estimate that neither government is likely to ignore, especially given the deteriorating economic and political climate in the DRC, and the relative scarcity of natural resources in Rwanda. It is therefore important that the science behind the extraction process is sound and the technology well monitored and maintained.

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Awards

Short-listed for the Wellcome Trust Science Writing Prize 2012:
For this article.

Welcome!

Astrobiology and the study of planets throughout the galaxy deal with some of the most profound questions regarding our existence: where did we come from, are there other worlds like ours out there, and are we alone?

I don't profess to be able to answer these questions, but that doesn't stop me from cobbling together some loosely coherent thoughts to share with interested readers. I find it helps me to maintain a cosmic perspective.

I completed a PhD in the Centre for Ocean and Atmospheric Science at the University of East Anglia in 2015, broadly focussed on planetary habitability, astrobiology, and global biogeochemical cycling on Earth.

I am also a committee member of the Astrobiology Society of Britain. Visit the ASB website for more information about astrobiology in the UK:

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